JP2000099160A - Pulse motor controller provided with high-accuracy return-to-origin function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse motor controller capable of performing a high- accuracy return-to-origin without executing the return-to-origin from a predetermined constant position concerning a device for driving an object through a pulse motor. SOLUTION: In the case of return-to-origin of the object, a section to turn on an origin sensor 18 is previously measured and stored in a memory 38. An origin position designating part 42 designates which position in this section is to be defined as an origin, and based on data in the memory 38, an origin stop position is calculated by an origin operating part 40. The calculated data are compared with the value of a light shield width counter 36 by an origin comparator part 44, and when the values are mutually coincident, the return-to- origin is performed by stopping an operating instruction pulse to the pulse motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse motor for controlling a pulse motor in an article positioning device or a movable carriage device in which a movable object such as a movable table or a movable carriage is translated by a pulse motor. Related to the controller. More specifically, the present invention relates to a home position return function of a pulse motor controller.

[0002]

2. Description of the Related Art In an article positioning apparatus, the origin return of a movable object such as a movable table or a movable carriage is performed in order to set a reference position for positioning. The home position return operation is performed by operating the pulse motor in response to the home position return command, stopping the drive signal to the pulse motor at the position where the signal is output from the home position sensor, and stopping the pulse motor. This position is called the origin as a reference position in machine control. Since the origin is a reference for control, it is required that the origin is always at a fixed position in the origin return operation.

In order to meet such a demand, in the prior art, for example, Japanese Patent No. 2653057 (Japanese Patent Laid-Open No.
As disclosed in No. 0), it has been proposed to improve the origin accuracy by an origin return method in which an origin return command is input from any position other than the origin and the origin can always be returned from the same direction to the origin position. ing. To explain the technique disclosed in this prior art document, in the articulated industrial robot shown in FIG. 4 of the publication, an arm is rotatable on a swivel that is rotatably mounted on a base. Attached, the swivel and the arm are generally driven by electric or hydraulic pressure. The home return operation of the arm is performed as follows.

A drive signal is output from a pulse motor drive circuit in accordance with a command from a central processing unit (CPU), whereby the pulse motor is rotated, and the rotational power of the pulse motor is transmitted by a speed reducer, whereby the arm is rotated. You. The rotation operation of the pulse motor is converted into a signal shown in FIG. 8 of the publication by a pulse generator and transmitted to the pulse counter and the origin pulse gate. The pulse counter counts the number of rotation pulses based on the A-phase and B-phase signals in FIG. This pulse counter determines how many pulses the pulse motor has rotated.

The origin pulse gate receives a Z-phase signal (FIG. 8). One pulse of the Z-phase signal is output for one rotation of the pulse motor. Therefore, the Z-phase signal is used as an origin pulse in the circuit of FIG. 1, and is taken into the central processing unit as an origin signal by a command from the central processing unit.
It is stored in the arm angle storage memory. On the other hand, the position information of the arm driven by the pulse motor is transmitted to the A / D converter as angle data by a potentiometer,
The data is converted into digital data and stored in the potentiometer voltage storage memory by the central processing unit.

In a general home position return method, FIG.
As shown in, the positions G and I where the origin pulse changes from OFF to ON according to the timing at which the origin return command is output at the position E and the position F are determined as the origin ON, The pulse motor is stopped by the next input position pulses H and J. For this reason, the stop position is shifted as indicated by H and J, which causes a malfunction in the position control.

Therefore, the accuracy of the origin position is improved by the origin return method shown in FIG. 2 of the same publication to which a sequence for moving to an arbitrary position other than the origin is added. That is, referring to FIGS. 2 and 3 of the publication,
When the home return command is received when the CPU is located at the point K in FIG. 3, the central processing unit reads the value of the potentiometer (step 20 in FIG. 2, P0 in FIG. 3), and then stores the potentiometer voltage storage memory. Among them, the value of the closest origin position is calculated (Step 21 in FIG. 2, Pi + 1 in FIG. 3), and the value of the target potentiometer is calculated (Step 22 in FIG. 2, P ′ in FIG. 3), The pulse motor is operated, and first, the pulse motor is moved to a predetermined point L. Thereafter, normal home return is performed, and the home pulse is recognized and stopped.

[0008]

Problems to be Solved by the Invention
The first problem of the method of returning to the origin described in the item (1) is that, when performing the return to the original point, it must first be moved to a predetermined arbitrary position (point L) other than the origin. The second problem is that the current stop position is measured by a potentiometer, compared with the origin pulse position in the vicinity, moved to any position other than the origin pulse position, and then returned to the origin position. If there is no mechanism for feeding back the rotation operation of the pulse motor as described above, this control method cannot be applied. The third problem is that when the Z-phase signal of the pulse generator is used for stopping the origin, one pulse is output for each rotation of the pulse motor, so that the stop position of the axis of the pulse motor is set at a certain angle. That is, it is fixed, and an arbitrary position during one rotation cannot be set as the origin.

An object of the present invention is to enable high-precision home position return. Another object of the present invention is to realize an origin return that does not require moving a movable object to an arbitrary position other than the origin at the time of origin return. Still another object of the present invention is to enable return to origin even in a control device such as a potentiometer that does not have a feedback function. Another object of the present invention is to realize high-precision return to origin by setting an arbitrary position of the motor rotation axis as the origin.

[0010]

According to the present invention, there is provided a pulse motor controller for controlling a pulse motor for driving a movable object. Means for detecting and storing the origin, and means for determining the origin stop position in the middle of the length. Upon returning to the origin, after the origin sensor senses light shielding by the light shielding plate, a predetermined position corresponding to the origin stop position is determined. After the output of the pulse, the output of the drive pulse to the pulse motor is terminated.

As will be described later with reference to the drawings, according to the present invention, regardless of whether the movable object returns to the origin from the forward or reverse direction with respect to the origin sensor, the movable object is always at the same origin stop position. Since it is stopped, the positioning of the movable object can be performed quickly and with high accuracy. In addition, since it is not necessary to return the movable object to the origin position from the same predetermined direction, the origin can be quickly returned.

In a specific embodiment, the length of the section where the origin sensor is shielded from light by the light-shielding plate is detected by a drive pulse output during a period in which the origin sensor is shielded from light by the light-shielding plate while the movable object is being driven. This is performed by counting the number, and the origin stop position is set at the middle point of this section.

[0013]

FIG. 1 shows a component positioning device as an example of a device to which the pulse motor controller of the present invention can be applied. Referring to FIG. 1, the component positioning apparatus includes a movable table 10 capable of translation.
The movable table 10 is translationally driven by the pulse motor 12 via a conversion mechanism that converts the rotational movement of the pulse motor 12 into the translation movement of the movable table 10. In the illustrated embodiment, the motion conversion mechanism comprises a lead screw 14 connected to the output shaft of the pulse motor 12, which meshes with an internal screw (not shown) provided on the movable table 10. As a conversion mechanism,
A belt transmission mechanism, a gear device, or the like may be used.

The pulse motor 12 is controlled by the pulse motor controller 16 of the present invention. Movable table 1
An origin sensor 18 is provided in the vicinity of the zero course. With respect to the origin sensor 18, a forward (+) limit sensor 20 is provided on the forward rotation direction side of the pulse motor 12, and a reverse (-) limit sensor 22 is provided on the reverse rotation direction side. Each of the sensors 18, 20, and 22 is composed of a photomicrosensor, and as shown in FIG.
And the light receiving section 26 has a slight width along the moving direction of the movable table 10. As shown in FIG. 1, the movable table 10 is provided with a light shielding plate 28 cooperating with the sensors 18, 20 and 22, and the light shielding plate 28 moves in accordance with the movement of the movable table 10. . The output signal of each of the sensors 18, 20, 22 is turned on, for example, when the light shielding plate 28 of the movable table 10 completely shields the light receiving portion 26 from light.
(High level). The signals of the sensors 18, 20, 22 are sent to the pulse motor controller 16. The pulse motor controller 16 performs processing in accordance with the type of the sensor and the operation command, and controls the pulse motor 12 to control the positioning of the table 10.

Next, referring to FIG. 3, the pulse motor controller 16 includes a pulse generator 32 for outputting a drive command signal S1 to the pulse motor driver 30. The pulse motor driver 30 receives the motor drive signal S1
2, the pulse motor 12 is driven. Pulse motor 1
The second driving force moves the table 10 via the lead screw 14. Sensor 1 as table 10 moves
When 8, 20, and 22 operate, the pulse motor controller 16 controls the drive command signal S1 according to the signal input to the pulse generator 32 of the pulse motor controller 16. That is, when the high-level signal S4 of the + limit sensor 20 is detected while the drive signal S1 is being output to the pulse motor driver 30, the pulse motor controller 16 stops outputting the drive signal S1 and the pulse motor 12 To stop. When the high level signal S3 of the origin sensor 18 is detected during the origin return operation command, the output of the drive signal S1 is stopped and the pulse motor 12 is stopped.
However, this signal is invalid during another operation command. Similarly,
When the drive signal S1 is output to the pulse motor driver 30, the high level signal S of the limit sensor 22 is output.
When 2 is detected, the pulse motor controller 1 stops outputting the drive signal S1 and stops the pulse motor 12.

Referring to FIG. 3, the components of the pulse motor controller 16 related to the home return function will be described. The pulse motor controller 16 includes a light-shielding width counter 36, a light-shielding width storage memory 38, an origin calculating unit 40, an origin position specifying unit 42, an origin comparing unit 44, and a central processing unit (C
PU) 46.

In the illustrated embodiment, the pulse motor controller 16 includes a counter input switching unit 34, and outputs a pulse signal S5 for operating the counter of the light shielding width counter 36 in response to a command from the CPU 46.
2 or the position pulse S11 from the rotary encoder 48 attached to the pulse motor 12 (the actual pulse motor 12 of the encoder signals A-phase, B-phase and Z-phase output from the encoder 48). (A-phase and B-phase position pulses representing the amount of rotation). However, in the simplest embodiment of the present invention, the encoder 48 and the counter input switching unit 3
4 is not essential and can be omitted. The light-shielding width counter 36 has a length (that is, a section in which the light-receiving portion of the origin sensor 18 is shielded from light by the light-shielding plate 28) (that is, a width of the section. The counter operation is performed by the pulse signal S5 output from the counter input switching unit 34, and the counter value S10 is always output to the origin position comparing unit 44. The light-shielding width counter 36
It is reset in response to the origin signal S3 from the origin sensor 18 and starts and stops.

The origin position specifying section 42 sets an origin stop position in any position in a section where the origin sensor 18 is ON (a section in which the light receiving portion of the origin sensor 18 is shielded from light by the light shielding plate 28). The data S8 for determining whether or not to do so is output to the origin calculation unit 40. The light shielding width storage memory 38 stores the light shielding width value S6 calculated by the light shielding width counter 36. The origin calculation unit 40 calculates the origin stop position based on the origin position S8 designated by the origin position designation unit 42 and the light shielding width data S7 of the light shielding width storage memory 38, and compares the origin stop position data S9 with the origin position comparing unit. 44. The origin position comparison unit 44 compares the origin stop position S9 calculated by the origin calculation unit 40 with the light shielding width data S10 from the light shielding width counter 36, and operates on the pulse generating unit 32 when the values match. A stop command pulse S13 is output to stop the motor 12.

Next, a sequence for measuring the light shielding width (the width of the section where the origin sensor 18 is turned on) will be described with reference to the flowchart of FIG. This light-shielding width detection sequence is performed when power is supplied to the pulse motor controller 16. Pulse motor controller 16
When the power is turned on, first, it is checked whether data exists in the light-shielding width storage memory 38 (step 100).
If data exists in the light-shielding width storage memory 38, it is confirmed whether the data can be rewritten (101). This is because when the light-shielding width storage memory 38 is formed of a nonvolatile memory such as a flash memory, an opportunity for data rewriting is given. The operator can give permission to rewrite data via an external input device (not shown) such as a keyboard connected to the CPU 46. If the data cannot be rewritten, an error occurs (102), and the process is interrupted.

When there is no data in the light-shielding width storage memory 38 or when the data may be rewritten, the operation of the pulse motor 12 is started to obtain the light-shielding width (103).
The table 10 that moves with the rotation of the pulse motor 12
As shown in FIG. 5, when the light-shielding plate 28 attached to the sensor completely blocks the light receiving portion of the origin sensor 18, the output signal of the origin sensor 18 turns ON (high level) (step 104).
State 51 in FIG. 5). The state 51 of FIG.
The side edge corresponds to a position (point A) where the edge coincides with the + side edge of the light receiving portion of the origin sensor 18. Origin sensor signal is O
Simultaneously with N, the light shielding width counter 36 is initialized (step 105), and the light shielding width counter 36 is started (106). The rotation of the pulse motor 12 is continued until the origin sensor signal is turned off (low level) (step 107, state 53 in FIG. 5). The state 53 in FIG. 5 corresponds to a position (point B) where the negative edge of the light shielding plate 28 coincides with the negative edge of the light receiving portion of the origin sensor 18.

When the origin sensor signal is turned off,
The rotation of the pulse motor 12 is stopped (Step 108),
The light shielding width counter 36 is stopped (109). As a result, a counter value is obtained while the origin sensor signal is ON, and this value is stored in the light shielding width storage memory 38 (110). Thus, the pulse motor controller 16
Is activated for the first time, the light shielding width is measured, and thereafter, the value is valid unless the value of the light shielding width storage memory 38 is destroyed or the origin sensor itself is changed. As can be seen from FIG. 5, the length of the section of the travel of the movable table 10 where the origin sensor 18 is shielded by the light shielding plate 28 (the light shielding width) is between the state 51 and the state 53. It is equal to the distance the plate 28 travels.

Next, the origin return operation of the movable table 10 by the pulse motor controller 16 will be described with reference to the flowchart of FIG. When the home position return command is executed, the CPU 46 acquires data of the home position specifying unit 42 (step 200). The origin position designating section 42 designates which position in the section where the origin sensor 18 is ON (the section between the state 51 and the state 53 in FIG. 5) is set as the origin. Are 、, の of the section
, Or by specifying the number of pulses. FIG. 5 shows, as an example, a case where the midpoint C of the section is specified. Alternatively, as shown in FIG. 5, it is possible to specify a point D that is at a distance of Δt1 from the state 51 and at a distance of Δt2 from the state 53. The origin is specified by an input from an external input device connected to the CPU 46.

Next, the value of the light-shielding width stored in the light-shielding width storage memory 38 is taken into the origin calculating unit 40 in accordance with a command from the origin position designating unit 42 (step 201). The origin stop position is calculated based on the value of the light shielding width taken from the memory 38 and the designation of the origin position designation unit 42 (202). When the origin stop position data is determined, the driving of the pulse motor 12 is started (2).
03). When the table 10 is moved by the rotation of the pulse motor 12 and the light shielding plate 28 attached to the table 10 blocks the origin sensor 18, the signal of the origin sensor is turned on (step 204; state 51 in FIG. 5).

At the same time as the origin sensor signal is turned ON, the light shielding width counter 36 is initialized (step 205), and the light shielding width counter starts (206). When the counter input switching unit 34 has switched to the pulse generation unit 32, the light shielding width counter 36 counts up in response to the signal S1 from the pulse generation unit 32, and the counter input switching unit 34 has switched to the rotary encoder 48. In this case, the light shielding width counter 36 is counted up by the position pulse signal S11 from the rotary encoder 48. The light shielding width signal S10 of the light shielding width counter 36 is sent to the origin position comparing unit 44, and the origin position comparing unit 44 compares the data S9 of the origin stop position calculated by the origin calculating unit 40 with the value of the light shielding width counter 36, When they match (step 207, state 52 in FIG. 5), the rotation of the pulse motor 12 is stopped (208). Thereby, the origin return of the table 10 is completed. With the above operation, in this embodiment, the section (A) where the origin sensor shown in FIG.
Movable table 1 with reference to the midpoint C of
Zero return is performed. Of course, an arbitrary point D among points A and B can be set as the origin.

Referring to FIG. 5, the home position return operation of the prior art will be compared with that of the present invention. In general home position return of the prior art, the pulse motor stops when the home position sensor signal is turned on. , The stop position of the movable table is in the state 51 (when returning to the origin from the negative side), or
The state becomes the state 53 (when the origin is returned from the + side). As a result, the origin stop position of the movable table is shifted substantially equal to the width of the light-shielding plate 28 (more precisely, the light-shielding plate 2 is shifted depending on whether the origin is returned from the negative side or the origin is returned from the positive side).
8), which is equal to the width obtained by subtracting the width of the light receiving portion of the origin sensor from the width 8). According to the present invention, the movable table can be positioned at a desired origin with high accuracy regardless of whether the origin is returned from the minus side or the origin is returned from the plus side. Also, any point such as point C (an intermediate point between points A and B) and point D can be set as the origin. Even when an arbitrary point such as the point D is set as the origin, the position can be stopped at the same point by calculating the position Δt1 from the − side and the position Δt2 from the + side, regardless of which direction the origin is returned. Can be.

Further, in the conventional control for stopping the movable object when the origin sensor is turned on, the origin sensor 18 is interrupted by vibrations of the pulse motor or the like despite the origin sensor being turned on (states 51 and 53). The signal of the origin sensor 18 is turned ON / OF due to the slight movement of the light shielding plate 28.
F may cause a malfunction, but according to the present invention, the point at which the state changes from OFF to ON (points A and B in FIG. 5).
Since the origin can be stopped at a position other than (point), malfunction can be prevented.

Although a specific embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications and changes can be made. For example, as described above, the encoder 48 and the counter input switching unit 34 can be omitted.

[0028]

As described above, the first effect of the present invention is that the home position return can be performed with high accuracy. A second effect of the present invention is that, in the home position return operation, the movable object is not moved to a certain position other than the home position,
This means that the home return operation can be performed quickly. A third effect of the present invention is that high-precision return to origin can be performed even in a control device such as a potentiometer that does not have a feedback function. Still another advantage is that the origin can be set at any position as long as the origin sensor is turned on.

[Brief description of the drawings]

FIG. 1 is a perspective view of a component positioning device to which a pulse motor controller of the present invention can be applied.

FIG. 2 is an enlarged perspective view of a sensor of the device shown in FIG.

FIG. 3 is a block diagram of a pulse motor controller of the present invention.

FIG. 4 is a flowchart showing the operation of the pulse motor controller of the present invention.

FIG. 5 is a diagram showing a relationship between an origin sensor and a light shielding plate.

FIG. 6 is a flowchart showing the operation of the pulse motor controller of the present invention.

[Explanation of symbols]

 10: movable table (movable object) 12: pulse motor 16: pulse motor controller 18: origin sensor 36/46: means for detecting light-shielding width 38: means for storing light-shielding width 40/42/46: determine origin stop position Means to do

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H303 AA01 BB01 BB06 BB11 CC01 DD03 EE10 FF06 HH05 HH09 LL03 LL09 MM08 5H580 AA03 BB09 FA04 FA14 FB03 FD12 GG03 HH02

Claims (3)

[Claims] 1. The translational motion of a movable object is controlled by controlling a driving pulse to a pulse motor for translationally driving the movable object, and the origin of the movable object is detected by an origin sensor responsive to a light-shielding plate interlocked with the movable object. In a pulse motor controller adapted to: a means for detecting and storing the length of a section where the origin sensor is shielded by the light shielding plate in the travel of the movable object, and determining the origin stop position in the middle of the length Means for returning to the origin of the movable object, after the origin sensor detects light shielding by the light shielding plate, and after the output of a predetermined pulse corresponding to the origin stop position, the output of the driving pulse to the pulse motor is terminated. A pulse motor controller characterized in that: 2. Detecting the length of a section in which the origin sensor is shielded from light by the light-shielding plate measures the number of drive pulses output during a period in which the origin sensor is shielded from light by the light-shielding plate during driving of the movable object. The pulse motor controller according to claim 1, wherein the control is performed by: 3. The pulse motor controller according to claim 1, wherein the origin stop position is a middle point of a section where the origin sensor is shielded from light by a light shielding plate.